<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <title>Boxmodel</title>
    <style>
        .div_css
        {
            margin: 25px ;
            border: 25px solid greenyellow;
            border-bottom-width: 50px;          /*覆盖前面25*/
            border-left-color: brown;
            border-right-style: outset;
            padding: 25px;
            width: 20%;
        }
    </style>
</head>
<body>
    <p>下面是25</p>

    <div class="div_css">
        全都是25
    </div>
</body>
</html>